Transparent touch panel and electronic apparatus

ABSTRACT

A transparent touch panel comprises a transparent first substrate ( 110 ) and a second substrate ( 130 ) that each has a transparent electro-conductive layer ( 111, 131 ) on one surface and that are arranged with a predetermined interval between each other such that the transparent electro-conductive layers ( 111, 131 ) are facing each other. Each of the transparent electro-conductive layers ( 111, 131 ) has a pair of electrodes ( 112, 112 ) and ( 132, 132 ) disposed on each end. Lead-out terminals ( 114, 114 ) and ( 134, 134 ) are connected to each electrode ( 112, 132 ) through surrounding circuits ( 113, 133 ) formed on the peripheral edges of the transparent first substrate ( 110 ) and the second substrate ( 130 ). Lead-out terminals ( 114, 134 ) are arranged on each of the opposing surfaces of the transparent first substrate ( 110 ) and of the transparent second substrate ( 130 ), and a plurality of holding members ( 80, 80 ), ( 81, 81 ) for holding the edges of the transparent first substrate ( 110 ) is provided. Each holding member ( 80, 81 ) is formed of an electro-conductive material. That portion of the holding member that is inserted between the transparent first substrate ( 110 ) and the second substrate ( 130 ) is disposed so as to be in contact with each lead-out terminal ( 114, 134 ). The transparent touch panel can be reduced in size and cost.

TECHNICAL FIELD

The present invention relates to a transparent touch panel and anelectronic apparatus comprising the transparent touch panel.

BACKGROUND OF THE INVENTION

The structure disclosed in Japanese Unexamined Patent Publication No.2002-259054 is known as that of a prior art transparent touch panel. Asshown in the exploded perspective view of FIG. 7, this transparent touchpanel is constructed by laminating a movable substrate 110 and a fixedsubstrate 130 via a spacer 140, which is a double-coated adhesive tape.The thickness of the double-coated adhesive tape is usually about 50-100μm. The movable substrate 110 has an input operation surface on thefront surface, which receives data input to the transparent touch panelby an operator using a pen or a fingertip.

The spacer 140 is formed into a frame-like shape, and adhered along theperiphery of the movable substrate 110 and the fixed substrate 130. Thespacer 140 comprises an excised section 141 that functions as an airvent, and a notch 142 to which a connector 120 (described later) isattached. When an air vent is unnecessary, the excised section 141 maynot be provided.

Dot spacers 160 are provided with a predetermined interval between eachother in the space between the movable substrate 110 and the fixedsubstrate 130 and surrounded by the spacer 140. A transparentelectro-conductive layer 111 and a transparent electro-conductive layer131 are formed on substantially the entire opposing surfaces of themovable substrate 110 and the fixed substrate 130 except for theperiphery. The transparent electro-conductive layer 111 formed on themovable substrate 110 has a pair of electrodes 112, 112, with one eachdisposed on each of the two ends. Lead-out terminals 114, 114 areconnected to the pair electrodes 112, 112 via a surrounding circuit 113formed on the periphery of the movable substrate 110.

The transparent electro-conductive layer 131 formed on the fixedsubstrate 130 has a pair of electrodes 132, 132, with one each disposedon each of the two ends. The pair electrodes 132, 132 are arranged sothat they are perpendicular to the pair electrodes 112,112 provided onthe movable substrate 110. Lead-out terminals 134, 134 are connected tothe pair electrodes 132, 132 via a surrounding circuit 133 formed on theperiphery of the fixed substrate 130.

The connector 120 comprises connecting terminals 122, 122 on its topsurface for being connected to the movable substrate 110, and connectingterminals 123, 123 on its bottom surface for being connected to thefixed substrate 130. Thermocompression bonding, etc., is used to attachthe connector 120 to the notch 142 of the spacer 140, thus connectingthe connecting terminals 122, 122 and the connecting terminals 123, 123to the lead-out terminals 114, 114 and lead-out terminals 134, 134respectively.

Recent years have seen a demand for reducing the number of parts used invarious equipment, in order to achieve miniaturization or costreduction. However, when a connector 120 is used as in theabove-described transparent touch panel, it is difficult to reduce thenumber of parts. In particular, remarkable drawbacks exist in using aconnector in portable electronic apparatuses, such as portable personalcomputers, mobile telephones, and personal digital assistants.

Japanese Unexamined Patent Publication No. 1989-221831 discloses atransparent touch panel that can be connected to an external devicewithout using an additional connector. This transparent touch panel hasa structure wherein the portion corresponding to the connector isintegrally formed with a movable substrate that is constructed of atransparent film. However, because this portion projects from theperiphery of the rectangular movable substrate, trimming loss thatoccurs in the transparent film when forming the movable substrateincreases, and therefore there is room for further improvement in termsof cost reduction.

SUMMARY OF THE INVENTION

The present invention has been accomplished to solve the above problems.An object of the present invention is to provide a transparent touchpanel and an electronic apparatus that can be miniaturized and whosecost can be reduced.

This object can be achieved by a transparent touch panel comprising: atransparent first substrate and a second substrate each having atransparent electro-conductive layer on one surface thereof, thetransparent first substrate and the second substrate being arranged witha predetermined interval between each other in such a manner that thetransparent electro-conductive layers are facing each other, and eachtransparent electro-conductive layer having a pair of electrodesdisposed on each end; a plurality of lead-out terminals being connectedto the electrodes through surrounding circuits formed on the peripheraledges of the first substrate and the second substrate, the lead-outterminals each being arranged on the opposing surfaces of the firstsubstrate and the second substrate; and a plurality of holding membersfor holding the peripheral edges of the transparent first substrate, theholding members being formed of an electro-conductive material andformed so that each of the portions inserted between the transparentfirst substrate and the second substrate is in contact with eachlead-out terminal.

The object of the present invention can also be achieved by anelectronic apparatus comprising the above-described transparent touchpanel and a display apparatus having connecting terminals, thetransparent touch panel being disposed on the display surface side ofthe display apparatus, and the holding members being in contact with theconnecting terminals.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an exploded perspective view of a transparent touch panelaccording to one embodiment of the present invention.

FIG. 2 is a side elevational view of the main part of an electronicapparatus using the transparent touch panel of FIG. 1.

FIG. 3 is a perspective view of a transparent touch panel according toanother embodiment of the present invention.

FIG. 4 is a side elevational view of the main part of the transparenttouch panel of FIG. 3 as seen from the arrow A.

FIG. 5 is a side elevational view of the main part of the fixedsubstrate of a transparent touch panel of still another embodiment ofthe present invention.

FIG. 6 is a side elevational view of the main part of a transparenttouch panel using the fixed substrate of FIG. 5.

FIG. 7 is an exploded perspective view showing a prior art transparenttouch panel.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereunder, embodiments of the present invention are explained withreference to the drawings attached. To make the structure easier tounderstand, each component in the attached drawings is partiallyexpanded or reduced and thus not shown in actual dimensions.

FIG. 1 is an exploded perspective view of a transparent touch panel ofthe present embodiment. In the structure of the present embodiment, thesame numerical symbols are used for the same constituent components ofthe prior art transparent touch panel shown in FIG. 7.

Various types of transparent plastic film can be used as the movablesubstrate 110. Specific examples thereof include polyethyleneterephthalate (PET), polyethylene naphthalate (PEN), polyether sulfone(PES), polyether etherketone (PEEK), polycarbonate (PC), polypropylene(PP), polyamide (PA), polyacryl (PAC), norbornene-based thermoplastictransparent resins, etc., or a laminate thereof. By laminating such atransparent plastic film or a laminate thereof with a polarizing plate,a phase plate, a hard coat film, a minute concave-convex film, etc., theflexibility, durability, and visibility at the time of inputting dataare improved. The thickness of the film is usually 20-500 μm.

The same materials for the movable substrate 110 may also be used forthe fixed substrate 130. It is also possible to use glass. In order toreinforce or improve the durability of the fixed substrate 130, asupport medium may be laminated on the fixed substrate 130. The supportmedium ordinarily used is formed of a polycarbonate resin substrate,acrylic resin substrate, polyolefin-based resin substrate, glass, etc.,and has a thickness of 0.5-5 mm. The support medium ordinarily used isflat, but the support medium may have a projection in the centerthereof.

The transparent electro-conductive layers 111, 131 on the movablesubstrate 110 and the fixed substrate 130 may be formed by a generalmethod for providing an electro-conductive material on a film substrate.Specific examples thereof include sputtering, vacuum deposition, ionplating and like PVD methods; CVD methods, coating methods, printingmethods, etc. The materials for the transparent electro-conductivelayers 111, 131 are not limited as long as they are transparent.Specific examples thereof include indium-tin complex oxide (ITO), tinoxide, copper, aluminum, nickel, chromium, etc. It is also possible toform transparent electro-conductive layers by laminating materials otherthan those mentioned above. Before forming the transparentelectro-conductive layer, an undercoat layer for improving thetransparency or adherence may be provided on the movable substrate 110or fixed substrate 130. Note that it is also possible to provide atransparent electro-conductive layer for shielding on the movablesubstrate 110 on the opposite surface to which the transparentelectro-conductive layer 111 is formed.

The transparent electro-conductive layers 111, 131 are formed so thatthe peripheries of the movable substrate 110 and the fixed substrate 130are exposed. The exposed portions can be obtained by forming thetransparent electro-conductive layers 111, 131 on the entire surfaces ofthe movable substrate 110 and the fixed substrate 130, forming a maskhaving a predetermined pattern on the surface of the transparentelectro-conductive layers 111, 131, peeling unnecessary portions of thetransparent electro-conductive layers 111, 131 by etching using an acidsolution, and removing the patterned mask by dissolving using a removersuch as an alkaline solution, etc. The transparent electro-conductivelayers 111, 131 may also be removed by using a laser instead of etchingwith an acid solution.

The pairs of electrodes 112, 112 and 132, 132 formed on both ends of thetransparent electro-conductive layers 111, 131 may be formed using aconductive ink. Silver, carbon ink, copper ink and like conductiveprintable pastes may be used as the conductive ink. Alternatively,silver and carbon may be mixed or recoated. The electrode usually has awidth of 0.2 mm to several mm, and a thickness of several μm to severaltens of μm. In order to maintain insulation and prevent migration,insulative ink may be applied to necessary portions of the transparentelectro-conductive layers 111, 131 or electrodes 112, 132 after formingthe electrodes 112, 132. Examples of usable insulative inks are acrylicresin, urethane resin, epoxy resin, silicon resin, etc.

In the peripheries of the movable substrate 110 and the fixed substrate130, surrounding circuits 113, 133 and lead-out terminals 114, 114 and134, 134 are formed, and the pairs of electrodes 112, 112 and 132, 132are connected to the lead-out terminals 114, 114 and 134, 134 via thesurrounding circuits 113, 133. The surrounding circuits 113, 133 and thelead-out terminals 114, 134 may be formed at the same time that theelectrodes 112, 132 are formed. The lead-out terminals 114, 114 of themovable substrate 110 and the lead-out terminals 134, 134 of the fixedsubstrate 130 are formed on the opposing surfaces of the movablesubstrate 110 and the fixed substrate 130 in such a manner that they areadjacent to each other.

The movable substrate 110 and the fixed substrate 130 are attached toeach other via a double-coated adhesive tape 140 having a thickness ofabout 50-100 μm. The double-coated adhesive tape 140 is formed byapplying an adhesive on both surfaces of a core film material. Examplesof the core film material include polyethylene terephthalate(PET),polyethylene(PE), polypropylene(PP), polyethersulfone(PES) and likeplastic films. Acryl-type, silicon-type, and urethane-type adhesive or amixture thereof may be used as an adhesive. In the double-coatedadhesive tape 140, notches 142 are formed in the portions correspondingto the lead-out terminals 114, 114 and 134, 134.

A plurality of clips 80, 80 and 81, 81 each having a U-shape side vieware attached to the fixed substrate 130. These clips 80, 80 and 81, 81are formed of a conductive metal material, and function as holdingmembers for sandwiching the periphery of the fixed substrate 130. In theportions where the clips 80, 80 are inserted between the movablesubstrate 110 and the fixed substrate 130, the top surfaces of the clips80, 80 are in contact with the lead-out terminals 114, 114 of themovable substrate 110. In the portions where the clips 81, 81 areinserted between the movable substrate 110 and the fixed substrate 130,the bottom surfaces of the clips 81, 81 are in contact with the lead-outterminals 134, 134 of the fixed substrate 130.

A transparent touch panel having the above-described structure caneasily be connected to an external electronic apparatus without using aconnector as in prior art techniques because the portions to beconnected to the external terminals are exposed by providing the clips80, 80 and 81, 81. FIG. 2 shows an enlarged view of the principal partsof an example of an electronic apparatus wherein a transparent touchpanel 100 is provided on the display surface of a display apparatus 90such as a liquid crystal display apparatus. In FIG. 2, a connectingterminal 92 is provided on top of the display apparatus 90, and theclips 80, 80 and 81, 81 of the transparent touch panel 100 are incontact with the connecting terminal 92. The portions of the clips 80,80 and 81, 81 which are in contact with the connecting terminal 92 arenot necessarily in the bottom of the touch panel but may instead be onthe side surfaces thereof.

In order to strengthen the connection between the connecting terminal 92and the clips 80, 80 and 81, 81, the connecting terminals 92 may beenergized in the upper direction using the elasticity of a spring, etc.It is also possible to provide a conductive adhesive between theconnecting terminal 92 and the clips 80, 80 and 81, 81. Paste conductiveadhesives, such as a two-component epoxy-based conductive adhesive(product No. 3380B, manufactured by Three Bond Co., Ltd.), arepreferably used.

The thickness of the portions in which the clips 80, 81 are insertedbetween the movable substrate 110 and the fixed substrate 130 ispreferably 0.5 to 2 times, and more preferably 0.8 to 1.4 times thespace between the movable substrate 110 and the fixed substrate 130.When this thickness is too thin, fitting the clips 80 is difficult andeasily causes faulty conduction. When this thickness is too great,faulty conduction or a fault in the winding of the movable substrate 110tends to occur because of the unduly enlarged space between the movablesubstrate 110 and the fixed substrate 130.

When the thickness of the portions in which the clips 80, 81 areinserted between the movable substrate 110 and the fixed substrate 130is greater than the space between the movable substrate 110 and thefixed substrate 130, it is preferable that a notched portion 119 beformed in the movable substrate 110 at the portion which is in contactwith the clip 80, as shown in FIG. 3. This allows only the portion ofthe movable substrate 110 in which the notched portion 119 is formed tobe warped upward with the clips 80 being inserted between the movablesubstrate 110 and the fixed substrate 130 as shown in FIG. 4. Thisprevents the whole movable substrate 110 from twisting. Using thepressing force generated by the warp of the portion in which the notchedportion 119 is formed, connection between the lead-out terminals 114,114 of the movable substrate 110 and the clips 80, 80 are secured. Eachscore of the notched portion 119 may be such that, as shown in FIG. 4,the movable substrate 110 independently exhibits flexibility inaccordance with each individual clip 80, 80 and 81, 81 or the portion ofthe movable substrate 110 in which the clips 80, 80 and 81, 81 areformed exhibits flexibility as a whole.

As shown in FIG. 5, a plurality of groove portions 139 may be formedcorresponding to the clips 80, 80 and 81, 81 in the periphery of thefixed substrate 130 on the surface opposite to that on which thetransparent electro-conductive layer 131 is formed. This holds thebottom portions of the clips 80, 80 and 81, 81 in the groove portions139 as shown in FIG. 6, preventing misalignment of the clips 80, 80 and81, 81.

The shape, dimensions, and thickness of the clips 80, 80 and 81, 81 arenot limited, and they may be strengthened by bending a portion thereof.Furthermore, the clips 80, 80 and 81, 81 may be formed of a metal foilas long as they can be attached to the transparent touch panel 100. Theclips 80, 80 and 81, 81 also need not be wholly made of metal but aresin may be used in some portions thereof.

In the present embodiment, a resistive film-type transparent touch panelwherein a space is formed between the movable substrate 110 and thefixed substrate 130 is explained; however, the present invention is alsoapplicable to a transmission capacitive-style transparent touch panelwherein an adhesive tape, etc., is provided on the entire surfacebetween the transparent electro-conductive layers 111, 131.

INDUSTRIAL APPLICABILITY

The present invention provides a transparent touch panel and anelectronic apparatus which enable miniaturization and cost reduction.

1. A transparent touch panel comprising; a transparent first substrateand a second substrate each having a transparent electro-conductivelayer on one surface thereof, the transparent first substrate and thesecond substrate being arranged with a predetermined interval betweeneach other in such a manner that the transparent electro-conductivelayers are facing each other, and each transparent electro-conductivelayer having a pair of electrodes disposed on each end; a plurality oflead-out terminals being connected to the electrodes through surroundingcircuits formed on the peripheral edges of the first substrate and thesecond substrate, the lead-out terminals each being arranged on theopposing surfaces of the first substrate and the second substrate; and aplurality of holding members for holding the peripheral edges of thetransparent first substrate, the holding members being formed of anelectro-conductive material and formed so that each of the portionsinserted between the transparent first substrate and the secondsubstrate is in contact with each lead-out terminal.
 2. The transparenttouch panel according to claim 1, wherein the thickness of the portionsof the holding members inserted between the transparent first substrateand the second substrate is 0.5 to 2 times the space between thetransparent first substrate and the second substrate.
 3. The transparenttouch panel according to claim 1, wherein the second substrate has anotched portion so that the portion/portions in contact with the holdingmembers has/have flexibility.
 4. The transparent touch panel accordingto claim 1, wherein the transparent first substrate has a plurality ofgroove portions in the surface opposite to the surface on which thetransparent electro-conductive layer is formed, and the holding membersare held in groove portions.
 5. The transparent touch panel according toclaim 1, wherein the transparent first substrate is a fixed substrate.6. An electronic apparatus comprising the transparent touch panel ofclaim 1 and a display apparatus having connecting terminals, thetransparent touch panel being disposed on the display surface side ofthe display apparatus, and the holding members being in contact with theconnecting terminals.